According to Bruce Baker, who heads the Energy Project, the driving local interest is in finding cleaner alternatives to the prescribed burns used to rid local forests of fuels that heighten risk of wildfires. It’s expected that forest waste from thinning projects would comprise between 75 and 85 percent of the fuel used to run the plant. With the rest coming from household trash and possibly from sludge left over from wastewater processing, the project could have the added benefit of solving some of the area’s waste removal issues.
The study is being funded by the U.S. Forest Service and APS, which has a legislative mandate to develop sustainable energy options. It is expected to be completed by this June and will include recommendations for next steps.
“This part of the study is a fatal flaw analysis where we’re looking for ‘deal breakers,’” said Mason at last Wednesday’s presentation. “The primary issue is feedstock, or the availability of fuel. It also has to make economic sense.”
During the week, Mason and Tornatore visited officials from Kaibab National Forest, Valle, the Park Service and Tusayan to assess the availability of potential fuels.
“When doing a fuel assessment, the consideration is if it’s sustainable.” Mason said. “Most plants are built on a 30-year life span so we look at long-term availability.”
He said that based on conversations with Kaibab officials, the project could have access to forest material from between 4,000 and 6,000 acres annually, representing about one fifth to sixth of acreage already approved for fuel reduction measures. Further study is needed to determine how much feedstock each acre would produce, as well as how much waste tonnage would be available from other sources in the region.
To secure financing for the project, they would have to demonstrate the availability of three to four times the fuel needed to power the two- to three-megawatt plant being explored, or between 75,000 to 100,000 tons annually. The sources would have to be close enough – no further than 50-70 miles away – to make economic sense.
“We have to look at the cost to collect, process and transport the materials,” Mason said.
While Mason looked at fuels, Tornatore described himself as “the environmental partner,” looking at emissions compliance and permitting issues.
“We are looking for what’s called ‘ultra-clean’ technology,” he said. “We’re looking worldwide for technology that meets air emissions standards and water usage, both concerns in this area.”
He said design would focus on an air-cooled plant using about two gallons of water per minute, probably from reclaimed sources. Transport of feedstock would require four or five truck trips per day.
He also explained how the gasification technology works.
“It’s not new technology,” he said, pointing to its widespread use during WWII, when gasoline was scarce and more than 1 million vehicles were powered by gasification using wood fuel.
Gasification differs from combustion in that little of the fuel is actually burned. Instead, the feedstock is subject to heat and pressure in an oxygen-controlled environment to chemically break it down, producing what’s known as “syngas,” or synthetic gas that can be used in the same way as natural gas to power the turbines that drive generators.
Tornatore said that the process lends itself to a greater diversity of fuels than direct combustion – one of the criteria TSS will be looking at when assessing potential equipment vendors. Ideal, he said, would be technology that can process multiple types of feedstock together in the same batch.
Gasification is also a cleaner method than direct combustion, he said and would produce hundreds of thousands of tons fewer emissions than controlled burns and wildfires.
It’s also more costly that direct combustion, which, Tornatore said, hasn’t been completely ruled out.
Potential sites are being studied in Tusayan and Valle.
Rather than purchasing the electricity, APS’ Don Keil said the company would prefer to own the plant outright and enter into long-term contracts for feedstock procurement. The electricity would be introduced to the power grid at a nearby substation and become part of the total energy pool.
Converting heat as a feasible by-product would require purchasers to be located in close proximity to the plant.
Tornatore said the industry standard for job creation is 4.9 positions per megawatt hour; in this case those jobs would primarily be concentrated in the area of gathering forest fuel.
Because the study is being funded with public money, it is considered a public document and will be available upon request.
Baker said the ongoing process is also open to the public and that he welcomes all comments and suggestions. Contact him at firstname.lastname@example.org or 638-0614.